Tag: astro2110

Could there be life in the Solar System other than Earth? According to NASA, there might be life in one of the oceans in the Solar System. I’m pretty sure that this question make you wonder which ocean is that? The answer is ocean in ENCELADUS.

Before I proceed on why there is potential life on Enceladus, let me introduce what is Enceladus first. Enceladus is the sixth largest moon of Saturn (about a tenth of Titan, Saturn’s largest moon).

In 2008, Cassini has discovered that Enceladus has a global subsurface saltwater ocean and now, molecular hydrogen which is one of the crucial things of life, has been found in the plumes of liquid shooting out from its surface. The presence of hydrogen is essential for microbes because they can use this gas to obtain energy by combining it with dissolved carbon dioxide (this process known as methanogenesis).

Enceladus Layers by WIREDBesides, based on the observation of plumes of liquid shooting out from its surface and its concentration of the hydrogen gas, scientists calculate that this gas is sufficient and to sustain a hypothetical colony of alien microbes.
Cassini’s Mission to Saturn and its Moons

In conclusion, whether humans are alone in this universe is still a great mystery. However, Cassini’s exploration build up some confidence that there are maybe places beyond Earth where life might exist and that could probably within reach of the spacecraft.

We usually defined a planet as something that orbits a star but this lone ranger a.k.a. nomad planet, rogue planet, free-floating planet, or orphan planet is unique since they do not orbit a star. Instead, they orbit the galaxy directly and considered as homeless world where they have neither sunrises nor sunsets (starless planet).

Migration appears to be quite common for planetary systems like the Jovian-type planets that migrate inward in some planetary systems due to close gravitational encounters in which one object loses energy and moves inward while other object gains energy and flung outward. Hence, it is reasonable to expect many planets have been ejected from their planetary system into interstellar space.

These planets are so difficult to detect directly because they are so dim, but how on Earth could we find them?

The best method for now is by using technique called gravitational microlensing. This technique takes advantage of gravity’s ability to bend light. These occur when massive object like a rogue planet passes between a star and Earth, the “lone ranger” acts as a lens which make the star’s light curve as seen from Earth. The lone ranger’s gravity warps the light of the background star causing it to magnify the same way as the lens work. In general, the bigger the planet, the more affected the light causing brightening events that can last for weeks which is way longer than small planets only last for few days or less.

One observational search found that these lone ranger might be twice as numerous as the stars in our galaxy. Therefore, the studies of the “lone ranger” are still going on and perhaps in the future, one of these planets could be Earth 2.0 .

We can study the Sun’s interior through three different ways and one of them is through observations of solar neutrinos produced by the nuclear fusion that power the Sun.

The nuclear fusion of proton and proton in the Sun produce deuterium, positron, neutrino that is responsible for almost 100% of the energy production by our Sun. Solar neutrinos contributes the largest flux of neutrinos from natural sources observed on Earth when make a comparison with atmospheric neutrinos and etc.

In principle, solar neutrinos give us the most direct way to study the nuclear fusion in the Sun’s core. This is because almost all of them pass straight through solar interior into space. However, neutrinos are difficult to detect but still possible since they do occasionally interact with matter and this could be done by using large detector.

The attempts to detect in the 1960s only found 1/3 of the expected number based on the Sun’s energy output. This disagreement is called solar neutrino problem and solved in the early 2000s. Based on the solution, neutrinos come in three different types:

Electron neutrinos

Muon Neutrinos

Tau Neutrinos

The problem that occurred in 1960s were because the early solar neutrino detectors could only detect electron neutrinos. Now, we know that neutrinos can change among the three types while passing through matter. In 1960s , the time solar neutrinos reach the detectors, only 1/3 are still electron neutrinos which resulted in the observation of only 1/3 of the expected number of neutrinos. In this modern era, we can be confident with this solution since the modern detectors can detect these types of neutrinos and confirmed that the number of solar neutrinos matches predictions. To learn more about neutrinos, there is a great link below here.

Generally, comets got kicked out from their home which are the Oort Cloud and the Kuiper Belt. This phenomena occur due to the pull of the gravity by planets or stars. Then, their journey of growing tails begin by moving toward the inner solar system.

Far from the Sun, small comets look the same as small asteroids, completely frozen and this dirty snowball is in solid form. As it approaches the Sun, it starts to heat up and ices begin to vaporize into gas that easily escapes the comet’s weak gravity. A combination of solar radiation pressure and the solar wind (stream of charged particles from the Sun) sweep the vaporize materials and dust back forming two separate tails :

An ion tail forms when UV from the Sun rips electrons from gas atoms in the coma (cometary), making them into ions through ionization. Then, the solar wind carries these ions away from the Sun resulting straighter and narrower tail.

On the other hand, a dust tail contains small particles (size similar with cigarette smoke). The reason this tail forms due to the presence of the solar radiation pressure that pushes on these particles, shoving them away from the nucleus of the comets. Due to the relatively weak pressure from the sunlight , the dust particles end up forming a diffuse and curved tail that typically appears white or pink relative from the Earth

Comets or asteroids typically hit the surface at a hyper-velocity (speed between 10 70 km/s) which releases enough energy to vaporize solid rock and blast out a crater. Crater comes from the Greek word for cup. Next, debris from the blast shoots high above the surface and then rains down over large area.Generally, craters are circular in shape because an impact blasts out material in all directions regardless of the direction of the impactor except for very low-angle impacts because it will create a significantly elliptical -shaped craters.

Dc = 1.8 ρa0.11 ρs-1/3 gp-0.22 (2R) 0.13 KE0.22 (sin θ) 1/3

Based on this equation, craters are typically about 10 times as wide as the objects that create them.Dcin this equation stands for the diameter of crater. Generally, a large crater may have a central peak and this peak forms when the center rebounds after impact in much the same way as the GIF below.

On the other hand ,Daniel Barringer was among the first to identify an impact crater which is the Meteor Crater in Arizona. For the crater specialists, this site is called the Barringer Crater in his honor. Below is the list of amazing craters on Earth.

The visible universe-including galaxies,stars and planets only make up 4 percents of the universe (REALLYYYY). What about another 96 percents of it? In reality, another 96 percents consists of the thing that is unseen. Besides, we can’t really identify or perhaps understand what that 96 percents is made up of. From the perspective of the scientists, they called it as a dark energy or dark matter. Why is it called as a dark matter/dark energy? (Say yes if you want to know more…kidding)

Dark matter is an unidentified type of matter and it does not interact with electromagnetic radiation (i.e. light), hence make it invisible to the electromagnetic spectrum. On the other hand, dark energy is basically an unknown form of energy which is have a direct relation with the accelerating rate of expansion of universe. However, it still remain as a hypothesis for the scientists.

According to the standard model of cosmology, dark energy contributes 68.3 percents of the total energy in the present observable universe. The mass–energy of dark matter contributes 26.8 percents while ordinary matter contributes 4.9 percents. If I were to explain these dark matter and dark energy,it is going to take forever….(I’m not even a scientist but probably will).

How do the dark energy have impact on the acceleration rate of the expansion of the universe? Dark energy has a unique property which is it has negative pressure which is distributed relatively homogeneously in space.

From this equation, it yields out a constant value for w (cosmic acceleration) thus prove that the universe is expanding with an accelerating rate. The derivation of this acceleration is shown in the link below.

The main point is we can work through a lot of mathematical formulas and do some estimation on the gravitational pull of these entities. However, there is no guarantee of proving what the unseen or so called invisible part of our universe is made up of but we do know that they are exist. Although it still remain as a hypothesis, the majority of the universe may still remain as a mystery. I provided a video in the link below which help to explain the dark matter and dark energy in a more intuitive way.

To explain this phenomenon, first, we need to know the exact definition of twinkling. The scientific name of the twinkling stars is astronomical scintillation. Twinkling/ scintillation, is a general term for variations in apparent brightness or position of a distant luminous object when viewed through a certain medium.

The main reason for this occurrence is due to the presence of thick layers of air turbulence (moving air) in the Earth’s atmosphere. This air turbulence causes twinkling because it is a continuous process of changing how starlight bent. In other words, as a starlight travels into our atmosphere, each stream of starlight is refracted .This refraction change the direction of the star, slightly due to the temperature gradient and different density layers in the Earth’s atmosphere.The random refraction of the starlight results in the twinkling of the star.

Hence, stars tend to twinkle more when they are closer to the horizon and windy (extreme turbulent) nights. WHY? This is because the light of stars near the horizon has to travel through denser layer of air compared to the light of stars overhead. Thus, more refraction occur. Above the atmosphere, if we viewed from outer space (or from a planet that didn’t have an atmosphere), stars do not twinkle at all.

A misconception holds that planets don’t twinkle in our sky. In reality, they actually do, but planets shine more steadily. This is because they are closer to the Earth,hence they appear big enough that the twinkling is not realizable although the light from these planets is also refracted by Earth’s atmosphere.Besides, the size of a planet on the sky cancels out the turbulent effects of the atmosphere, hence a stable image is presented to the human’s eyes.

However, we might see the planets twinkling if we see them lower in the sky. This phenomenon occurs because there are more turbulence effects and in the direction of any horizon, we are looking through more atmosphere compared when we look overhead.

Now, shall we continue with our song earlier?

Twinkle, twinkle, little star,How I wonder what you are!Up above the world so high,Like a diamond in the sky.

A long time ago, in a galaxy far far away……too much of Star Wars (inside joke). I bet most of us in the entire world probably heard of Copernicus. However, only little of us knew about Aristarchus of Samos, ( Ἀρίσταρχος ὁ Σάμιος, Aristarkhos ho Samios-his name in Greek) an ancient Greek astronomer and a mathematician I would say who first proposed a ‘Sun-Centered Solar System’ eighteen centuries before Copernicus.WOW! ( I can see the face of the enthusiasm among all of you).

However, the Greeks rejected his astronomical ideas that the Earth goes around the Sun especially from the two famous astronomers: Aristotle and Ptolemy, which are now known to be incorrect. Do you know why did they reject the real explanation for planetary motion?

Although there were many reasons the Greeks were reluctant to abandon their original idea (Earth-centered universe), the most ultimate reason was their inability to detect stellar parallax. Stellar parallax is a parallax on an interstellar scale, means that there is slight apparent shifts in stellar positions over a course of the year. Since stellar parallax is only detectable with telescopes, his accurate astronomical theory was unprovable at the time. Besides, his theory did not gain wide acceptance until almost 2000 years later.To know more about the stellar parallax, there are few links that I shared in this post.

Since there is no observable stellar parallax, he suggested that the Stars were extremely very far away.Why? This is because parallax is a function of distance. In other words, distant objects exhibiting smaller parallax than nearer objects. To further strengthen his argument, he estimated the sizes of the Moon and the Sun. He estimated the Moon’s size by observing the shadow of Earth on the Moon during a lunar eclipse and measured the angle between the Moon and the Sun at first and third quarter phases of the Moon. Based on these experiments, he concluded that the Sun must be larger than the Earth hence he believed that Earth should be the one that is orbiting the Sun.

Just to let you know, you are going to join a marvelous adventure with me. Therefore, to make everything smooth, I will introduce myself a little bit. The handsome guy in this picture is me (please don’t laugh).

Photo by me.

I am a sophomore studying mechanical engineering and originally from Malaysia. If you have not been here, do visit and explore the extraordinary place. Lastly, my name is Mohamad Ali Yazdani MEHRDAD YAZDANI.